Method of developing tread pattern

Abstract

A method of designing a tread unit that may be repeated in succession about the circumference of a tire to produce an acoustically acceptable tread pattern. The impact of an initial design of a tread unit on a road surface is simulated so that a determination of the number of pulses contained in the impact may be made. An analysis is then performed, based on the number of pulses, as to whether the tread unit design satisfies a predetermined acoustic criteria. If the tread unit design satisfies the acoustic criteria, it may be incorporated into the tire tread pattern. Otherwise, the method may be repeated with a modified tread unit design until the predetermined acoustic criteria is satisfied.

What is claimed:  
     
       1. A method of developing a tread pattern comprising the steps of: 
       importing a tread unit design;  
       simulating the impact of the tread unit design on a road surface;  
       determining the number of pulses contained in the simulated impact;  
       analyzing, based on the number of pulses, whether the tread unit design satisfies a predetermined acoustic criteria;  
       performing said importing, simulating and analyzing steps until an acoustically satisfactory tread unit design is identified which satisfies the predetermined acoustic criteria; and  
       repeating in succession said acoustically-satisfactory tread unit design to develop the tread pattern.  
     
     
       2. A method as set forth in  claim 1 , wherein said analyzing step comprises multiplying the number of pulses by the expected number of tread units in the tread pattern and comparing this product to a predetermined value. 
     
     
       3. A method as set forth in  claim 2 , wherein said comparing step comprises verifying whether the product is greater than 100. 
     
     
       4. A method as set forth in  claim 1 , wherein said simulating step comprises digitizing the tread unit design, constructing an impact model using the digitized tread unit and footprint leading edge geometry, and generating tread unit impact signals from the impact model. 
     
     
       5. A method as set forth in  claim 4 , wherein said digitizing step comprises digitizing the tread unit design on a coordinate system so as to define load-supporting portions of the tread unit design which would contact with the pavement and distinguish them in binary form from those portions of the tread unit design which would not contact the pavement. 
     
     
       6. A method as set forth in  claim 5 , wherein said digitizing step comprises representing the digitized tread unit by a matrix of “1's” and “0's” with the “1's” representing the load-supporting portions and the “0's” representing grooves and slots in the tread unit design. 
     
     
       7. A method as set forth in  claim 4 , wherein the constructing step comprises providing a known footprint leading edge geometry. 
     
     
       8. A method as set forth in  claim 4 , wherein the constructing step comprises assuming that leading edge radius of the footprint is infinity. 
     
     
       9. A method as set forth in  claim 4 , wherein said constructing step comprises adding the “1's” and “0's” along the footprint leading edge at any given position in the circumferential direction. 
     
     
       10. A method as set forth in  claim 4 , wherein said generating step comprises generating the impact signals by applying the impact model as the footprint leading edge moves from one end of the tread unit to the other end of the tread unit in the circumferential direction. 
     
     
       11. A method as set forth in  claim 1 , wherein said determining step comprises performing a Fast Fourier Transform analysis on the impact signals generated by the impact model. 
     
     
       12. A method as set forth in  claim 1 , wherein said determining step comprises determining whether any of the first six harmonics in the transformed impact signals is at least twice larger than the largest preceding harmonics. 
     
     
       13. A method as set forth in  claim 1 , wherein said determining step comprises assuming the number of pulses in the impact signals being the number representing the harmonics which is at least twice larger than the largest preceding harmonics. 
     
     
       14. A method as set forth in  claim 1 , wherein said determining step comprises assuming the number of pulses in the impact signals is one. 
     
     
       15. A method as set forth in  claim 1  wherein said repeating step comprises repeating the tread unit design in a plurality of pitches.